github / github/app

Copilot: Not sending user-agent on MCP Oauth register

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#3,799 1 comment 3 reactions 0 assignees View on GitHub

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Description

For some MCP services, when connecting a custom MCP server with OAuth, the DCR flow begins but fails at /register because Github Copilot does not send a User-Agent header. It is common to have protective rules requiring headers such as User-Agent on a request.

Example case where /register is denied due to missing User-Agent:
Image


Field Value
App version 1.1.19
OS macOS 26.6.2
Theme GitHub
Path /
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Research direction

Reproduce the OAuth DCR flow against a custom MCP server and inspect the request sent to /register. Confirm the request headers, then verify that the registration succeeds when the required User-Agent header is present.

Written by the indexing model from the issue text.

Assessment

Domain
authentication, desktop
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
68/100

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